Bad Forensics: A Main Cause of Wrongful Convictions

TV viewers are addicted to forensic cop shows – CSI, NCIS, etc etc. The shows make it look like every crime can be solved by forensics and that forensic science is unassailable. In fact, bad forensics is one of the leading causes of wrongful convictions across the country. When I talk about “bad forensics” I group several categories of problems under that heading.

1. Mistakes – Often crime labs and crime scene detectives mishandle the material to be tested or the material has been tampered with by witnesses and bystanders before the police even get there. I had a case where the main evidence against the accused was that there were traces of gunpowder on his jacket which had been found at the scene of the crime. But during our investigation, we discovered that prior to sending the jacket off for testing, the police had taken several photographs of the jacket in an effort to record its condition prior to testing. They chose the most brightly lit room at the precinct to do so, which happened to be the precinct’s gun locker and storage facility. Police officers routinely cleaned their weapons in the room before and after firearm testing. Laying the jacket on the bare floor of that facility practically guaranteed that some gunpowder would transfer onto the sleeves. (It also explained why our expert – who tested it – also found traces of gunpowder on the back of the jacket.)

That same type of transference can happen with the holy grail of forensic evidence – DNA. While no one questions the validity of DNA evidence, as the science has allowed DNA to be found and identified from smaller and smaller samples, there is often no attempt to consider transference of DNA by touching objects that contain another persons’s DNA. Forbes Magazine recently reported on a study conducted by a group of scientists from Indiana. The study explained that current technologies used by forensic laboratories are now reading DNA profiles from low-template and low-quality samples, that have “not been systematically investigated.” Their conclusion was startling: Touch transfer DNA “could falsely link someone to a crime” and forensic scientists relying on modern high-sensitivity equipment could “falsely conclude that DNA left on an object is a result of direct contact.” Their findings also showed that it is impossible to scientifically determine whether the tiny bits of DNA came into contact with evidence from a direct source or from a secondary source. Also, and more frightening, no matter how much they tried to sanitize their experiment, unknown third-party DNA was nonetheless able to make its way into the results, highlighting the plausibility of cross-contamination with touch-transfer DNA.
The Forbes article focused on a case that I have previously spoken about and examined – that of Oklahoma City Police Officer Daniel Holtzclaw who was convicted of sexual assault. Miniscule trace amounts of DNA -invisible to the naked eye – were allegedly found on Officer Holtzclaw’s pants. But the evidence also showed that Officer Holtzclaw searched the accuser’s purse for evidence before he was swabbed for DNA. Going through the accuser’s personal belongings, his hands would likely come into contact with lots of her DNA. He then used the restroom, touching his pants in the process. The Indiana study tells us that it would be highly probable that a touch transfer of DNA could have occurred. In fact, consistent with touch-transfer DNA, an unaccounted-for and unknown male’s DNA had also been found on Holtzclaw’s pants. Nevertheless, the prosecutor told the jury that the speck of female DNA evidence was conclusive proof of sexual contact between Holtzclaw and the victim, and then, unsupported by his own evidence, claimed that the particular DNA came from the victim’s vagina —a scientifically impossible conclusion. Nevertheless, the jury found Holtzclaw guilty and sentenced him to 263 years in prison.

2. Misconduct – Sometimes, the crime lab techs just make results up. Over the last few years, many crime labs have been found to have employees and scientists who just straight up fabricated results. In 2013, the New York City Medical Examiner’s office confirmed that it was reviewing more than 800 rape cases from a 10-year period during which DNA evidence may have been mishandled by a lab technician who resigned in 2011 after an internal review uncovered problems with her work. The review uncovered dozens and dozens of cases in which DNA evidence was commingled with DNA evidence from other cases.
Also in 2013, a former chemist at a Massachusetts State drug lab was indicted on 27 counts of obstructing justice, tampering with evidence, perjury and other charges in connection with her handling of some of the tens of thousands of drug cases she worked on during her nine years there. “Little Annie” Dookhan is accused of faking test results, intentionally contaminating and padding suspected drug samples, forging co-workers’ signatures on lab reports, and falsely claiming to have a master’s degree in chemistry.
A few months before that, the St. Paul, Minn., police department’s crime lab suspended its drug analysis and fingerprint examination operations after two assistant public defenders raised serious concerns about the reliability of its testing practices. A subsequent review by two independent consultants identified major flaws in nearly every aspect of the lab’s operation, including dirty equipment, a lack of standard operating procedures, faulty testing techniques, illegible reports, and a woeful ignorance of basic scientific principles.
In Oklahoma City, home of the Holtzclaw case, crime lab analyst Joyce Gilchrist earned the nickname “Black Magic” for her uncanny ability to always find some forensic evidence tying the accused to the crime. She was exposed in 2001 after an investigation showed that she provided false evidence in a large number of cases. Her work sent 21 people to death row, twelve of whom were executed before they were exonerated. (By the way, how’s that support for the death penalty doing?)
The book “The Cadaver King and the Country Dentist” by Radley Balko and Tucker Carrington painfully and in great detail explains how an untrained medical examiner and a local dentist in Mississippi built a million dollar plus practice by simply falsifying findings and creating an alleged expertise in bite mark evidence. Many of their cases have been overturned and the people they sent away exonerated.
As bad as that was, it pales in comparison to West Virginia where crime lab analyst Fred Zain produce forensic matches in cases where others could not. The first ever DNA exoneration in the United States exposed Zain as a fraud who lied about his credentials and faked evidence in countless cases. The West Virginia Supreme Court undertook a special investigation into his work and concluded that Zain wrongfully convicted as many as 134 people.
I could go on and on but I hope you got the point. How does this happen? Think about it – often, the State gets the first crack at testing the evidence. In many cases, there may not be enough material to test or the mishandling of the evidence may prevent the defense from doing its own testing. So the State’s expert gets to say what they want without any fear or real contradiction.

3.Junk Science This last area deals with two issues- (a) untested and unproven scientific theories that are put before juries as gospel and (b) exaggeration of the validity or accuracy of testing methods. For years, the FBI had metallurgists who would testify that they could match bullets to each other by their specific lead content. So they would take a bullet found in a body and match it to a bullet found on the defendant or in their home and say they were a match. But then a retired FBI decided to test out the theory and established that it was completely unsupportable by scientific study. There was no way to reliably match the bullets by lead content because numerous manufacturers used the exactly same lead content. In a study conducted following his report, an FBI scientist admitted giving false testimony about lead bullet analysis in a Kentucky case and estimated that the technique has been used in about 2,500 cases since 1980 and has been mentioned in court testimony about 500 times since then.
Overstating the accuracy of forensic testing also caused an FBI scandal more recently. Hair fiber analysis has been a lynch-pin of forensic testimony in criminal cases. Scientists regularly testified that they can pinpoint – almost with DNA’s accuracy – that a hair fiber came from the defendant or the victim. Turns out they can’t. After a 2015 Washington Post report exposed the falsity of the analysis, the Office of Inspector General did a lengthy investigation into the FBI Crime Lab Hair Analysis Unit. The results were horrifying. Flawed forensics were used in at least 60 capital punishment cases, the OIG report found.
Fourteen defendants were either executed or died in prison. The OIG’s report criticized “the use of scientifically unsupportable analysis and overstated testimony by FBI lab examiners in criminal prosecutions.”
The Washington Post reported that of 28 examiners within the microscopic hair comparison unit, 26 overstated forensic matches in ways that favored prosecutors in more than 95% percent of the 268 trials reviewed. The study revealed:

(a) Microscopic hair analysis could not scientifically distinguish one individual to the exclusion of all others.
(b) Statistical weight could not be given to comparisons to suggest a likelihood that the hair derived from a specific source.
(c) Expert witnesses should not cite the number of hair analyses they had conducted in the lab to bolster the idea that they could definitively state that a hair belonged to a specific individual.

Over the past few years, advanced understanding in the science of hair types has left hair analysis, as a forensic tool, in tatters. Today’s consensus by real experts is more straightforward than ever: there is nothing that can credibly be said, by FBI-approved analysts or anyone else, about about the frequency with which particular characteristics of hair are distributed in the human population. Yet for decades, it was seen as rock-solid proof of an accused’s guilt. Countless people have gone to jail based on nothing more than an expert claiming they found a hair that definitively matched the accused or the victim; yet know its been proven to be virtually worthless as a method of identifying someone. It can only safely be used to rule out a suspect as the source of crime-scene materials or in combination with the vastly more accurate technique of DNA testing.

So what’s the message? We need to be much more careful when we give the seal of approval to forensic expertise that comes from a government crime lab. History has shown us that serious flaws have been discovered all too late for some people. Even when an accepted and accurate form of science like DNA is brought before a jury, we need to make sure that the defense has access to its own testing which should occur at the same time as the prosecution tests it, if at all possible. The defense also needs to be allowed to examine the methods and conditions under which the material was isolated and tested. Time and time again we have seen that allowing the State to put forth scientific evidence without safeguards leads to horrific results.